Contact device



2,894,995 Patented July 7, 195$ CONTACT DEVICE Bengt Ludvig Wijkman, Stockholm, Sweden, assignor to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden, a corporation of Sweden Application June 22, 1955, Serial No. 517,188

Claims priority, application Sweden July 8, 1954 7 Claims. (Cl. 200-104) This invention relates to electric connecting devices, electromagnetic relays and the like, and relates more exactly to a contact device for such connecting devices.

In signal and safety installations for railways there are particular demands on the connecting devices for reasons of safety. Such a demand is that in a spring type contact device comprising make and break contacts the fusing of the contact members of a contact prevents the make of contacts of the opposite kind but effects the break of the other contacts of the same kind. Such an effect is possible to achieve in a manner known per se if the movable contact members of the contacts are actuated by means of a common control device (lifting stud, lifting strip), so that the movable contact members of the different contacts may mechanically operate each other by means of the control device.

According to the invention the intended effect is achieved in such a way that the movable contact members are substantially immovable at least in a direction away from the respective stationary contact members in relation to the control device, and the statioary contact members are movable from a normal position in the direction towards the pertaining movable contact members a fixed distance; which is accurately predetermined preferably by stops, that, when a stationary contact member and a movable contact member are fused together, the stationary contact member will follow the movable contact member such a long path of the movement of the control device, so that the other contacts of the same kind as the fused contact members are broken without closing the contacts of the opposite kind.

The invention will be described more closely in connection with the attached drawing, in which Fig. 1 shows schematically a contact device made in accordance with the invention, forming a part of a relay, Fig. 2 shows a fixed contact member forming a part of the contact device according to Fig. 1, Fig. 3 illustrates the invention applied to a spring set having a more conventional performance, Fig. 4 illustrates another principle of the present invention, and Fig. 5 is a perspective front view of the arrangement shown in Fig. 1.

Fig. 1 illustrates a control device 1, which has the shape of a strip of insulating material. This is, in a suitable way, slidably controlled in the longitudinal direction so as to be movable up and down between two end positions, the lower end position representing the unactuated position and the upper end position representing the actuated position of the contact device. The strip 1 is normally kept in its rest position by means of a pressure spring 2, which is schematically shown as a screw spring, which, however, can consist of a plate spring of a type conventionally used for spring sets. The lower end 3 of the strip 2 is actuated by the armature of the electromagnet, not shown, so that the strip is displaced to its upper end position when the armature is attracted and restored to its rest position by the spring 2 when the armature is released. Transversal pins 4 are inserted in holes in the strip 1, which pins form the movable contact members of the contact device. The stationary contact members are indicated with St: and 5b and are of substantially L-shape as shown in Fig. 2. These stationary contacts are suitably made of resilient wire, for instance Phosphor bronze wire, and each of them comprises a comparatively long part 6, a shorter part 7 extending substantially perpendicular to the longer part 6, and a contact part 8, which is mainly parallel with the part 6. If the material of the wire is unsatisfactory for contact purposes there is on the contact part d suitably a sleeve 9 of contact material. At the shown embodiment two stationary contact members, 5a and 512 respectively, cooperate with each movable contact member 4, one stationary contact member being arranged on each side of the strip 1 and each having its contact part 8 turned towards the strip 1 and running perpendicularly to the longitudinal direction of the pertaining pin 4. The stationary contact members are at the end of the part 6 that is opposed to the part 7 fastened behind to the body of the contact device or the relay, so that the end that is fastened cannot turn round the longitudinal axis of the part 6. This fastening is indicated at 149 in Pig. 2. The part 6 is most easily protected against turning by being provided at its end with a bent part, which for instance can mesh with a slot in a plate or the like, which is also provided with holes or grooves for the {parts 6 of the stationary contact members and serve as a holder for the stationary contact members. Each stationary contact member has its part 6 rotatably supported at least near the part 7, which is indicated at 11 in Fig. 2. The part 6 is in this way prevented from being bent, when the contact is actuated, so that the contact part 8 becomes movable up and down solely through the torsional influence.

The top of the contact device in Pig. 1 includes four make contacts, two for each of the two top pins 4, and four lower break contacts, two for each of the two lowest pins 4. In the break contacts the respective pins 4 rest in rest position against the contact sleeves d on the stationary contact members, which, when influenced by the pressure from the pressure spring 2, are turned so much as to maintain the desired contact pressure. In the make contacts the respective pins 4 are to be found in a predetermined distance from the contact ends of the stationary contact members, which distance is the desired contact distance. The stationary contact members of the make contacts are accordingly in an unactuated neutral position, which, owing to the shape of the stationary contact members described above and their principle of elasticity, may be established very exactly and maintained unaltered during the operation of the relay. When at the operation of the relay the strip 1 is lifted to its upper end position, the pins 4 of the break contact are normally leaving the pertaining stationary counter contact members and the pins 4; of the make contacts are instead pressed against the contact sleeves a on the stationary contact members pertaining to the make contacts, which Contact members are turned upwards in a suitable angle to achieve the desired contact pressure, while the stationary contact members of the break contacts take their neutral positions. When the strip 1 returns to its test position, when the relay is released, the pins i or" the make contacts are normally removed from the pertaining stationary contact members so as to make these return to their neutral positions while the pins 4 of the break contacts are again pressed against their respective stationary contact members, whereby accordingly the rest position shown in Fig. 1 will be again occupied.

The stationary contact members 5a and 5b are connected to outer conductors preferably so, that in each circuit those two contacts which cooperate with the same pins 4 are in series. In such a case the pins 4 need not be connected with outer conductors. The series connection of the contacts causes on one hand a greater breaking capacity, and perhaps the most important thing, on the other hand it will be possible to achieve breaking of a circuit even though a contact path comprised in the same may be welded, which often is a further condition for contact devices in safety installations in addition to those mentioned at the beginning.

To achieve the intended eifect in case that a contact path should be welded there are for the stationary contact members 50 and 5b comprised in break contacts in relation to the body of the contact device or the relay fixed stops 12a and 12b, and fixed stops 13a and 13b for the stationary contact members comprised in make contacts. If for instance the lower left break contact is assumed to be welded at the operation of the relay the lower left stationary contact member So will follow the lowest pin 4 when the strip 3 is moving upwards. When the said contact member 5a reaches the neighbouring stop 12a, the upward movement of the strip 3 will be stopped, so that it remains in the position determined by the stop 12a. In this position the lowest pin 4 has left the lower right stationary contact member 551, so that that circuit, in which the welded contact path is comprised, is broken. The pin 4 lying closest over the same has also left the stationary contact members in and 5b comprised in the other two break contacts, so that these break contacts are also open. The path of movement permitted by the said stop 12a is however not sutficient to make the two upper pins 4, in the make contacts, make contact with the respective stationary contact members 5a and 5b, whereby it is guaranteed that those circuits, in which the make contacts are comprised,

will not be closed.

If at the release of the relay a make contact path is fused the downward movement of the strip 3 will be limited in a corresponding manner by the stop 13a and 13b, respectively, located under the stationary contact member 5a and 5b, respectively, comprised in the welded contact path, whereby in a similar manner the result will be that all the other make contacts are opened without the break contacts being closed.

For very obvious reasons it is a condition of obtaining the desired effect that the lifting force of the relay armature and the spring power of the pressure spring are sufficiently great to overcome the straightening power (or the pro-tension in the rest position at constructions where such a pre-tension may be found) of at least one but preferably more stationary contact members.

At the shown embodiment there is a stop 12a and 12b respectively 130: and 13b for all stationary contact members irrcspectively of whether they are part of make or break contacts, in spite of the stops with the indica tions 12 being used only in break contacts and stops with the indication 13 being needed only for make contacts. This depends on the fact that the shown group of contacts is intended to be disposed optionally for diflerent combinations of make and break contacts with an optional placing of these within. the contact device. Thus the strip 2 may be provided with at least a series of holes with equal spacing for make contacts located in such a way in relation to the stationary contact members as is indicated by the top pins 4 and with at the least a series of holes with equal spacing for break contacts located in such a way in relation to the stationary contact members as is indicated by the two lowest pins 4 and in these holes the pins 4 may be inserted alternatively. The position of the holes in one series in relation to the position of the holes in the other series is determined by the fact that if the functions of the break contacts are to take place earlier than, simultaneously with or later than the functions of the make contacts. Many series of holes provided with holes which are mutually a little displaced 4 may possibly be arranged for the functions of the make and/ or break contacts due to which it is possible to vary the conditions of the time between not only contact functions of different kind but also contact functions of the same kind. At such a construction it is presumed that the stationary contact members have fixed positions, i.e. in a holder which is comb-like or provided with holes, in which positions the contact members may be fixed in some suitable way, e.g. be cemented.

If make and break contacts should be produced this may occur either by inserting an additional stationary contact member, e.g. at the top of the shown contact device on the under-side of the stops 13a and 13b, respectively, or at the bottom of the same on the upside of the stops 12a and 12b, respectively. Another possibility for producing make and break contact functions is to be connect electrically a pin 4 included in make contacts with a pin 4 included in break contacts, and for instance combine the corresponding stationary contact members on one side of the strip 3 with each other and the conductor, the connection of which is to be changed, while those conductors, between which the connection of the first-mentioned conductor is to be changed, are connected to the two remaining stationary contact members. A third manner of producing make and break contact functions is to connect an outer conductor to a pin 4 and place the pertaining stationary contact members on one side of the strip 3 above the pin and on the other side of the strip 3 under the pin. The pins 4 may for the rest generally be connected to outer conductors or exchanged for contact springs, so that the stationary contact members, co-operating with each movable contact member, are instead constituting two make or break contacts connected in parallel with the said movable contact member.

The arrangement shown in Figure 5 represents the stage in which fusion has taken place between the right part of the upper pin 4 and the corresponding contact 9 at an upper end position of the strip 1, 3 (in which upper position the two upper pins 4 are pressing against the contacts 9). At the release of the relay from the upper position and the downward movement of the strip 1, 3, this movement will be limited, as illustrated, when the fused contact member 51; reaches the stop 13b. During the movement of the upper pin 4, the series connected left contact 9, 4 is broken. The movement of the pins 4 has, however, been so limited that the two lower pins 4 have not yet reached the contacts. The manner in which the respective contacts now operate will become apparent.

The contact device shown in Fig. 3 is a spring set of, broadly speaking, conventional performance with stationary and movable contact members, in the shape of plate springs, whereby the stationary springs are indicated by 14, 15, 16 and 17, while the movable springs have the indications 18, 19, 20 and 21. The spring set is shown schematically from the contact ends of the springs and their fastening ends are presumed to be joined together mutually and fixed to a frame, e.g. a relay bridge, in some known manner, e.g. by means of insulating binding screws, passing through the fastening ends of the springs and insulating spacers, arranged between them. For the adjustment of the movable contact springs there is a removable control stud 22 which is displaceable in its longitudinal direction and in a known manner actuated by for instance a relay armature and a resetting spring. The control stud 22 is provided with teeth 23, 24, 25 and 26 which in the shown schematical embodiment co-operate with flaps, protruding from the movable contact springs. Of these contact springs the springs 18 and 19 are make contacts while the springs 20 and 21 are break contacts. The movable springs have in a known manner a pre-tension in the direction towards the pertaining fixed contact springs and the teeth of the control stud are altogether on the side of the respective movable contact spring that is turned towards the stationary contact spring, co-operating with said movable contact spring.

Contact make in the make contacts as well as in the break contacts will thus be produced by the spring tension of the movable springs, while contact break is produced forcibly by the teeth of the stud, removing the contacts of the movable springs from the stationary springs in overcoming the spring tension of the movable contact springs.

For the determination of the position of the contact ends of the stationary contact springs there is a fixed supporting stud 27. In known spring sets, working according to the basic principle indicted here, the stationary contact springs are generally fixedly arranged in the supporting stud. To achieve the effect intended with the present invention the stationary contact springs 14-17 are instead slightly movable as-preferably with a pretensionthey rest against one edge of recesses 28, 29, 30 and 31 in the supporting stud, said recesses having such a width, that the necessary movement of the stationary contact springs'is allowed. .111 the recesses 28 and 29 of the stationary contact springs 14 and 15, comprised in the make contacts, the upper'edges 32 and 33, respectively, thus serve as stops for fixing the normal position of the contact springs and the lower edges 36 and 37 serve as stops for limiting the movement of the control stud 22 in case of a contact welding of the make contacts, while in the recesses 30 and 31 of the stationary springs 16 and 17 comprised in break contacts the lower edges 34 and 35 serve as stops for fixing the normal position of the contact springs and the upper edges 38 and 39 function as stops in case the break contacts should be fused. It is to be understood that a fundamental condition for achieving the desired effect is that the width of the recesses 2831 is below the normal contact distance, though enough for permitting a sufficient, yet reduced breaking distance in the other contacts of the same kind as the one fused.

In practice the studs 22 and 27 are suitably arranged in the central plane of the spring set, e.g. so that they extend-in a manner known per se-through holes in the contact springs.

The device shown in Fig. 3 may also be modified in such a manner that the movable contact springs are fixedly connected to the control stud 22, whereby they need not be pre-stressed. For obtaining the contact pressure the stationary contact springs should then be movable in the direction from the stops 36-39, for which reason the rest position should be determined substantially by the directing force of the stationary springs only, without the aid of stops, similar to the steps 32-34 in Fig. 3.

To fulfill the condition that a break should take place in a circuit, in which a fused contact is included, two make contacts and, respectively two break contacts are suitably connected in series in each circuit.

In Fig. 4 is shown a principle, deviating from the basic principle indicated above for solving the invention problem mentioned at the beginning.

The stationary contact springs 4011-4361 and 40b-43b respectively are here rigidly supported in rigid supporting studs, 48a and 4811, respectively, substantially without any possibility to move in the direction towards the pertaining movable contact springs 44a-47a and 4412-471), respectively. The movable contact springs are pre-tensioned and controlled by lifting studs 49a and 4%, respectively, in a manner completely similar to the manner for the device according to Fig. 3. If in this device a contact path should be fused, this means that the respective control stud will be fixed mainly to one of its endpositions, depending on the fact if it is a make contact or a break contact that is fused. Contacts which are already closed, will thus remain closed and contacts already opened will remain opened. However, all contacts are doubled, owing to the fact that they exist in two spring sets actuable by a common armature 50.

In welding a make contact the individual resetting springs 51a and 51b, respectively, restores the spring set, in which the fused make contact is not included, to the rest position, when the armature is released, and as each make contact or break contact in one spring set is connected in series with a make contact or a break contact in the other spring set there will arise a break of all circuits.

If instead there arises a fusing of a break contact it must however-so as to achieve the desired break of all circuits--be possible to actuate the spring set having faultless contacts. This is not possible to achieve if the armature in a common way directly actuates the control studs, as in such a case a prevented movement in one stud would prevent the armature from moving, thus also preventing the actuation of the other stud. According to the invention there are thus found between the armature and the conrol studs resilient links 52a and 52b which yield if the respective control studs are prevented from moving upwards. These resilient links may e.g. be made as plate springs, fixed to the side of the armature or the lifting arm turned from the control studs. The respective control stud is thus actuated by one end of the spring that is flexible downwards but pre-tensioned so, that the mentioned end rests against the under-side of the armature with a predetermined spring pressure. This pressure is selected in such away that the spring, when the armature is attracted, does not normally yield to the load, arising on the control stud though it is yielding if the upward movement of the control stud is stopped by the welding of a break contact, whereby consequently the armature may be attracted without being stopped by the fused break contact and actuate the faultless spring set. The fiat springs (leaf springs) described above may of course be replaced by springs of another kind, e.g. disk springs, which with a certain initial pressure press the individual frames of the control studs against the under-side of the armature.

It might further be easily understood, that the movable contact springs may be rigidly connected to the control studs, if instead the stationary contact springs are arranged to move a little in the direction from the pertaining movable contact springs thus guaranteeing in a manner known per se the distribution of the contact pressure.

In all the embodiments described above the stationary and/ or movable contact members may of course be provided with twin contacts in a manner known per se.

I claim:

1. A contact spring assembly for an electromagnetically actuated switching device, said assembly comprising sets of make and break contact, each of said sets including a pair of flexible stationary contacts connected in series and a mated movable contact member adapted to bridge the two contact elements of the pair, a common actuating member joining all said contact members for simultaneously moving the same between positions closing each set of make contacts and opening each set of break contacts, and a limit stop for each stationary contact, each of said stops being fixedly mounted relative to the respective stationary contact at a distance therefrom more than the distance of movement at which the associated movable contact member becomes disengaged from the respective engaged contacts, but less than the distance of movement at which the contact member of another set closes its associated contacts, each of said stops being disposed to abut against the corresponding stationary contacts upon flexing thereof to an extent in excess of said distance of disengagement, whereby upon a stationary fiexible contact being fused to its associated contact member resulting in the abument of the fused contact against the respective stop during movement from a closed toward an open circuit relationship is operative to limit movement of said common actuating member to prevent movement of other contacts in an open circuit relationship toward a closed circuit relationship.

2. A contact spring assembly according to claim 1, wherein a second limit stop is disposed on the opposite side of each flexible stationary contact spaced apart therefrom as hereinbefore defined to limit flexing of fused contacts in both directions.

3. A contact spring assembly according to claim 1, wherein each of said flexible stationary contacts comprises a springy elongated member forming an angle in one plane, one arm of said member being fixedly mounted and the other being engageable by the respective contact member, whereby said contact experiences a torsional deflection by coaction with its contact member.

4. A contact spring assembly according to claim 1, wherein each of said flexible stationary contacts com prises a springy wire having a straight first portion, a straight second portion extending at a right angle from the first portion and a straight third portion extending at a right angle from the second portion in the direction toward the free end of the first portion, said free end of the first portion being fixedly mounted and said third portion being engageable by the respective contact member whereby said contact experiences a torsional deflection by coaction with its contact member.

5. A contact spring assembly according to claim 1, wherein said sets of make and break contacts and said limit stops are mounted one above another, and wherein said common actuating means comprises an axially displaceable bar disposed between the pairs of contacts of said sets and mounting a transverse contact arm for each pair adapted to bridge the contacts of each pair.

6. A contact spring assembly according to claim 1, wherein each of said flexible stationary contacts comprises a leaf spring, one end of each spring being fixedly mounted and the other end being engageable by the respective movable contact member, and further comprising a comb-shaped member fixedly mounted relative to said leaf springs, each of said leaf springs engaging the gap between two adjacent teeth of said comb member, the width of said gaps being such as to permit movement of the flexible stationary contacts for a distance more than the distance of movement at which the associated contact member becomes disengaged from the engaged contact elements but less than the distance of movement at which the contact member of another set closes its associated contact elements.

7. A contact spring assembly according to claim 6, wherein said movable contact members are in form of leaf springs each mating with a flexible stationary contact, and wherein said common actuating member comprises a comb-shaped moving stud, each of said movable contact members engaging the gap between two adjacent teeth of the stud.

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